Dependency Injection prototype

src/common/services/InstantiationService.ts

@@ -0,0 +1,81 @@
+/**
+ * Copyright (c) 2019 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { IInstantiationService, IServiceIdentifier } from 'common/services/Services';
+import { getServiceDependencies } from 'common/services/ServiceRegistry';
+
+declare const console: any;
+
+export class ServiceCollection {
+
+  private _entries = new Map<IServiceIdentifier<any>, any>();
+
+  constructor(...entries: [IServiceIdentifier<any>, any][]) {
+    for (const [id, service] of entries) {
+      this.set(id, service);
+    }
+  }
+
+  set<T>(id: IServiceIdentifier<T>, instance: T): T {
+    const result = this._entries.get(id);
+    this._entries.set(id, instance);
+    return result;
+  }
+
+  forEach(callback: (id: IServiceIdentifier<any>, instance: any) => any): void {
+    this._entries.forEach((value, key) => callback(key, value));
+  }
+
+  has(id: IServiceIdentifier<any>): boolean {
+    return this._entries.has(id);
+  }
+
+  get<T>(id: IServiceIdentifier<T>): T {
+    return this._entries.get(id);
+  }
+}
+
+export class InstantiationService implements IInstantiationService {
+  private readonly _services: ServiceCollection = new ServiceCollection();
+
+  constructor() {
+    this._services.set(IInstantiationService, this);
+  }
+
+  public setService<T>(id: IServiceIdentifier<T>, instance: T): void {
+    this._services.set(id, instance);
+  }
+
+  public createInstance<T>(ctor: any, ...args: any[]): any {
+    const serviceDependencies = getServiceDependencies(ctor).sort((a, b) => a.index - b.index);
+
+		let serviceArgs: any[] = [];
+		for (const dependency of serviceDependencies) {
+			let service = this._services.get(dependency.id);
+			if (!service) {
+				throw new Error(`[createInstance] ${ctor.name} depends on UNKNOWN service ${dependency.id}.`);
+			}
+			serviceArgs.push(service);
+		}
+
+		let firstServiceArgPos = serviceDependencies.length > 0 ? serviceDependencies[0].index : args.length;
+
+		// check for argument mismatches, adjust static args if needed
+		if (args.length !== firstServiceArgPos) {
+			console.warn(`[createInstance] First service dependency of ${ctor.name} at position ${
+				firstServiceArgPos + 1} conflicts with ${args.length} static arguments`);
+
+			let delta = firstServiceArgPos - args.length;
+			if (delta > 0) {
+				args = args.concat(new Array(delta));
+			} else {
+				args = args.slice(0, firstServiceArgPos);
+			}
+		}
+    console.log('args', args, 'serviceArgs', serviceArgs);
+		// now create the instance
+		return <T>new ctor(...[...args, ...serviceArgs]);
+  }
+}